1. Field of the Invention
The present invention relates to generator tuning systems for electronic organs, and more particularly, a multiple octave generator tuning system that provides detuning between octaves and thereby results in enhanced musical effects.
2. Description of the Prior Art
Multiple octave tuning systems for electronic organs are known in the art. For example, U.S. Pat. No. 3,450,825--Cunningham, discloses a system of locked-octave generator ranks that provides a celeste effect in an electronic organ. U.S. Pat. No. 3,004,460--Wayne, discloses an audio modulation system using continuous phase changers for achieving an ensemble effect in electronic organs using a locked octave generator rank. In addition, U.S. Pat. No. 3,049,959--Meyer, discloses a method of obtaining ensemble and celeste effects in electronic organs which use locked octave generator ranks. U.S. Pat. No. 3,816,635--Uetrecht, also discloses tone generator systems for electronic organs that allow production of the notes of the musical scale from a single oscillator. Some of the prior art systems (Meyer, Cunningham) programmed the outputs of differently tuned divide-by-two locked octave generator ranks alternately to overcome to some extent the ensemble disadvantages of "locked" generators. However, the presently disclosed system has an improved stretched programming scheme which provides unlocked scales for individual stop groups and provides parallel stretched scales for better celeste effects. The prior art (Wayne) discloses that an optimum celeste tuning requires less percentage detuning for the high notes than for the low notes. However, Wayne's method did not use multiple generator ranks but instead modulated tonal outputs from a single rank. Meyer's multiple generator ranks did not provide the desired taper to the detuning. Cunningham used two non-overlapping locked octave generator ranks to obtain a celeste and tuned the higher pitched rank flat (compressing the celeste pitch scale) in an attempt to achieve the desired taper. Because the presently disclosed system uses parallel stretched generator groups it makes it possible to have several degrees of optimally tapered celeste detuning with only a single locked octave celeste generator rank. This is advantageous both musically and economically.